Abstract The overall objective of the Host Response Monitoring Core is to provide centralized, comprehensive and consistent immune monitoring to enhance the activities of the Atlantic Coast Sexually Transmitted Infection Cooperative Research Center investigators. The shared scientific/resource core will provide expertise in systemic and mucosal immunity with an emphasis on humoral, cellular and biomarker analysis. To accomplish Core goals the efforts and expertise of Dr. Sempowski's cellular immunology lab and Dr. Staats' mucosal immunology lab have been united. Centralized immune monitoring assays have been divided into three specific aims. 1) Humoral Responses: Provide antibody quantity and isotype assessment by ELISA, and antibody quality (avidity) by surface plasmon resonance. 2) Cellular Responses: Provide mucosal tissue procurement, cellular subset isolation, polychromatic flow cytometry/cell sorting, and functional in vitro restimulation assays for comprehensive host response monitoring to both challenge pathogens and experimental vaccines/adjuvants. Supporting technologies include analysis of the frequency of cytokine producing cells by intracellular staining and flow cytometry, and ELISpot. 3) Multiplex Biomarker Analysis: Provide targeted multiplex protein array profiling of biological samples, such as culture supernatant, serum/plasma, urine or inflammatory exudate, using the luminex bead array platform (Mouse and Human). This technology has the capability of simultaneously quantifying up to 50 distinct analytes (e.g. cytokines, chemokines, hormones, signaling transduction proteins) in a single 50 uL sample. This core will be utilized by all AC-STI-CRC research projects and is critical to the success of the center.